BUSCADOR RECOLECTA

In this paper, we present a study of the laser scribing of WOx, VOx, and MoOx films, deposited onto crystalline silicon, with three different wavelengths (355 nm, 532 nm, and 1064 nm) and in two temporal regimes in pulse width, picosecond and nanosecond. For each case, we measure the fluence threshold to remove the transition metal oxides (TMO) film and the fluence threshold to induce damage in the crystalline silicon substrate. The relation between the process parameters and the morphological changes produced in the oxide films is also analysed. The selection of the proper laser source allows a wide parametric window, leading to the complete removal of the TMO films without alteration of the crystalline silicon substrate. Morphological changes of the ablated regions were characterized through confocal microscopy and the relationships between the dimensions of the craters and the ablation parameters were analysed.

Finally, we present results on the isolation of diodes and their electrical characteristics, showing the quality of the laser scribing processes.

Laser-Induced Forward Transfer (LIFT) is a very versatile technique, allowing the selective transfer of a wide range of materials with no contact and high accuracy. This work includes the analysis of heterojunction silicon solar cells with the frontal grid deposited by LIFT, and the electric characterization of the deposited lines.

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In this article, we study the effect of the inversion charge ( Q inv ) in a solar cell based on the hole-selective characteristic of substoichiometric molybdenum oxide (MoO x ) and vanadium oxide (VO x ) deposited directly on n-type silicon. We measure the capacitance–voltage ( C – V ) curves of the solar cells at different frequencies and explain the results taking into account the variation of the space charge and the existence of Q inv in the c-Si inverted region. The high-frequency capacitance measurements follow the Schottky metal–semiconductor theory, pointing to a low inversion charge influence in these measurements. However, for frequencies lower than 20 kHz, an increase in the capacitance is observed, which we relate to the contribution of the inversion charge. In addition, applying the metal–semiconductor theory to the high-frequency measurements, we have obtained the built-in voltage potential and show new evidence about the nature of the conduction process in this structure. This article provides a better understanding of the transition metal oxide/n-type crystalline silicon heterocontact., The authors would like to acknowledge the CAI de Técnicas
Físicas of the Universidad Complutense de Madrid. The authors
would also like to thank the Mexican grants program CONACyT
for its financial collaboration., Peer Reviewed

This document is the Accepted Manuscript version of a Published Work that appeared in final form in The journal of physical chemistry letters, copyright © 2023 The Authors. Published by American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/full/10.1021/acs.jpclett.3c00643, Poly(amidoamine) (PAMAM) dendrimers are used to modify the interface of metal-semiconductor junctions. The large number of protonated amines contributes to the formation of a dipole layer, which finally serves to form electron-selective contacts in silicon heterojunction solar cells. By modification of the work function of the contacts, the addition of the PAMAM dendrimer interlayer quenches Fermi level pinning, thus creating an ohmic contact between the metal and the semiconductor. This is supported by the observation of a low contact resistivity of 4.5 mO cm2 , the shift in work function, and the n-type behavior of PAMAM dendrimer films on the surface of crystalline silicon. A silicon heterojunction solar cell containing the PAMAM dendrimer interlayer is presented, which achieved a power conversion efficiency of 14.5%, an increase of 8.3% over the reference device without the dipole interlayer., This research has been supported by the Spanish government
through Grants PID2019-109215RB-C41, PID2019-
109215RB-C43, and PID2020-116719RB-C41 funded by
MCIN/AEI/10.13039/501100011033. Thomas Tom acknowledges the support of the Secretaria d’Universitats i
Recerca de la Generalitat de Catalunya and the European
Social Fund (2019 FI_B 00456). In addition, the authors
thank the technical staff from Barcelona Research Center in Multiscale Science and Engineering from the Universitat
Politecnica ̀ de Catalunya for their expertise and helpful
discussions over the XPS results, Dr. Oriol Arteaga from the
Universitat de Barcelona for the ellipsometry measurements,
and Guillaume Sauthier from the Catalan Institute of
Nanoscience and Nanotechnology for his contribution to
UPS measurements and their discussion., Peer Reviewed

© 2021 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, Laser-Induced Forward Transfer (LIFT) is a very versatile technique, allowing the selective transfer of a wide range of materials with no contact and high accuracy. This work includes the analysis of heterojunction silicon solar cells with the frontal grid deposited by LIFT, and the electric characterization of the deposited lines., Partial financial support for this work has been provided by the Spanish Ministry of Science and Innovation under the
projects CHENOC (ENE2016-78933-C4-1-R and ENE2016-78933-C4-4-R) and SCALED (PID2019-109215RBC41 and PID2019-109215RB-C44)., Peer Reviewed

In this work, a new design of transparent conductive electrode based on a graphene monolayer is evaluated. This hybrid electrode is incorporated into non-standard, high-efficiency crystalline silicon solar cells, where the conventional emitter is replaced by a MoOx selective contact. The device characterization reveals a clear electrical improvement when the graphene monolayer is placed as part of the electrode. The current–voltage characteristic of the solar cell with graphene shows an improved FF and Voc provided by the front electrode modification. Improved conductance values up to 5.5 mS are achieved for the graphene-based electrode, in comparison with 3 mS for bare ITO. In addition, the device efficiency improves by around 1.6% when graphene is incorporated on top. These results so far open the possibility of noticeably improving the contact technology of non-conventional photovoltaic technologies and further enhancing their performance., This research was funded by MCIN/AEI/10.13039/501100011033, grant numbers PID2019-109215RB-C41 and PID2019-109215RB-C42., Peer Reviewed

© 2022 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, Surface passivation is of paramount importance in photovoltaic devices based on high-quality crystalline absorbers such as crystalline germanium (c-Ge). In this work, we report on the surface passivation of p-type c-Ge by an amorphous silicon carbide/aluminium oxide film stack (a-SiCx/Al2O3). In particular, we focus on the impact of the thin (0, 1, 2, and 4 nm) a-SiCx interlayer which is used to provide chemical passivation while the Al2O3 is responsible for the field-effect passivation due to its high negative fixed charge density. The measured effective surface recombination velocity (Seff) values show that the introduction of the a-SiCx interlayer improves surface passivation, but the thinner the a-SiCx film the better. High frequency capacitance-voltage characterization leads to the determination of the fixed charge density (Qf) which indicates that the a-SiCx is shielding the negative charge located at the first nanometers of the Al2O3 film, as suggested by chemical characterization of the interface. As a consequence, the best result is Seff = 18 cm/s for the case of 1 nm of a-SiCx., This work has been supported by the Spanish government under projects PID2019–109215RB-C41 (SCALED), PID2020–116719RB-C41 (MATER ONE) and PID2020–115719RB-C21 (GETPV) funded by MCIN/AEI/10.13039/501100011033. The authors would like to thank the master student Guillem Ayats for his help in processing the samples, Dr. Alejandro Datas from Instituto de Energía Solar (IES) in Madrid for providing the c-Ge wafers and Dr. Rodrigo Fernández-Pacheco of the Laboratorio de Microscopias Avanzadas (LMA-INA) of Zaragoza for the EELS analysis., Peer Reviewed

This is the peer reviewed version of the following article: Tom, T. [et al.]. Deoxyribonucleic acid-based electron selective contact for crystalline silicon solar cells. "Advanced materials technologies (Weinheim)" [en línia], 10 Febrer 2023, [Consulta: 12 Desembre 2022]. Disponible a: http://hdl.handle.net/2117/377832, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1002/admt.202200936. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited., Development of carrier selective contacts for crystalline silicon solar cells has been recently of great interest toward the further expansion of silicon photovoltaics. The use of new electron and hole selective layers has opened an array of possibilities due to the low-cost processing and non-doping contacts. Here, a non-doped heterojunction silicon solar cell without the use of any intrinsic amorphous silicon is fabricated using Deoxyribonucleic acid (DNA) as the electron transport layer (ETL) and transition metal oxide V2O5 as the hole transport layer (HTL). The deposition and characterization of the DNA films on crystalline silicon have been studied, the films have shown a n-type behavior with a work function of 3.42 eV and a contact resistance of 28 mO cm2. This non-doped architecture has demonstrated a power conversion efficiency of 15.6%, which supposes an increase of more than 9% with respect to the cell not containing the biomolecule, thus paving the way for a future role of nucleic acids as ETLs., T.T. and E.R. shared co-first authorship. This research was supported
by Spanish government through grants PID2019-109215RB-C41,
PID2019-109215RB-C43, and PID2020-116719RB-C41 funded by MCIN/
AEI/10.13039/501100011033. One of the authors (T.T.) acknowledges
the support of the Secretaria d’Universitats i Recerca de la Generalitat
de Catalunya and European Social Fund (2019 FI_B 00456). Besides
this, the authors thank technical staff from Barcelona Research Center
in Multiscale Science and Engineering from Universitat Politècnica de
Catalunya for its expertise and helpful discussions over XPS results,
Dr. Oriol Arteaga Barriel from Universitat de Barcelona for the thickness
measurements, and also Guillaume Sauthier from Catalan Institute of
Nanoscience and Nanotechnology for his contribution through UPS
measurements and discussions., Peer Reviewed

DOI link format: http://dx.doi.org/10.1016/j.mtener.2022.101182
© 2022 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, The functionalization of structural nanoengineered battery-type electrodes has aided the emergence of supercapattery (SCp) subclass, which enables a wide range of applications. Herein, our research work provides a platform for two-step fabrication of nanoengineered 3D-on-2D structure as a promising approach to obtain high-performance battery-type electrodes. The hierarchical 2D NiCo bimetallic LDH NC(12)40 electrode was fabricated using electrodeposition, while the nanoengineered 3D ZIF-67 on 2D LDH electrode was achieved via pseudomorphic replication techniques. The fabricated 3D-on-2D NC(12)40-30 electrode reveals a maximum areal capacity of 1044 mC cm-2 at a current density of 4 mA cm-2 in 6 M KOH electrolyte. Furthermore, NC(12)40-30//AC was integrated as a SCp device, achieving a maximum specific capacitance of 63 F/g and maximum specific energy and power of 20.5 W/h/kg and 8522.7 W/kg, respectively, with improved capacitance retention (85%) even after 10,000 cycles. Thus, the assembled SCp coin cell displays 18-LED illumination in four different commercial LED colors, indicating the viability of the battery-type electrode for SCp development., This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2014R1A6A1030419) and by the National Research Foundation of Korea (NRF) Grant funded by the Korean government (MSIT) (No. 2020112382). This work has been partially supported by the Spanish government under project PID2019-109215RB-C41 (SCALED)., Peer Reviewed

© 2023 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, Thermophotovoltaics has become a very attractive solution for heat-to-electricity conversion due to its excellent conversion efficiencies. However, further research is needed to reduce the device cost which is typically based on III-V semiconductors. To tackle this limitation, crystalline germanium (c-Ge) has been proposed as an excellent substrate for low-cost devices. One of the key advances behind high system efficiencies is the excellent reflectance of the out-of-band photons at the rear surface of the photovoltaic device. These photons with lower energy than the absorber bandgap are reflected back to the thermal emitter reducing its thermal losses. In this work, we explore the performance of hole selective contacts based on evaporated transition metal oxides (MoOx, VOx, WOx) to be introduced at the rear surface of c-Ge devices. Regarding electrical properties, we characterize the selectivity of the contact by measuring effective surface recombination velocity (Seff) and contact resistivity (¿C). Best results are obtained with MoOx contacted by Ag/ITO with Seff = 588 cm/s and ¿C = 55.6 mO cm2 which can be improved by using gold as a metal contact leading to Seff = 156 cm/s and ¿C = 60.9 mO cm2. Regarding out-of-band reflectance, it is better for the case of Ag/ITO/MoOx contact with 87.5% compared to 78.9% for Au/MoOx when a 1473 K black body spectrum is used. Device simulations show potential system efficiencies in the range of 18–19% which are comparable to the best reported efficiencies using c-Ge thermophotovoltaic devices., This work has been supported by the Spanish government under
projects PID2019-109215RB-C41 (SCALED), PID2020-116719RB-C41
(MATER ONE) and PID2020-115719RB-C21 (GETPV) funded by MCIN/
AEI/10.13039/501100011033. The authors would like to thank the
master student Oscar Llados ´ and Guillem Ayats for their help in processing the samples, Dr. Alejandro Datas from Instituto de Energía Solar
(IES) in Madrid for providing the c-Ge wafers and fruitful discussions., Peer Reviewed

The interdigitated back-contacted (IBC) solar cell concept has been extensively studied for single-junction cells and more recently as a good choice for three-terminal tandem devices. In this work, carrier-selective contacts based on transition metal oxides deposited by atomic layer deposition (ALD) technique are applied to IBC c-Si(n) devices. In the first part of the study, we develop a hole-selective contact based on thin ALD vanadium oxide (V2O5) layers without using an amorphous silicon interlayer. The ALD process has been optimised, i.e. number of ALD cycles and deposition temperature, as a trade-off between surface passivation and contact resistivity. Noticeable surface passivation with recombination current densities around 100 fA/cm2, as well as reasonable contact resistivity values below 250 mOcm2 are reached using 200 ALD V2O5 cycles deposited at a deposition temperature of 125 °C (~10 nm layer thickness). The optimised ALD V2O5-based contact is combined with both an ALD TiO2-based electron-selective contact and an excellent surface passivation in non-contacted regions provided by ALD Al2O3 films, to form a fully ALD IBC c-Si(n) solar cell scheme. Fabricated devices yield photovoltaic efficiencies and pseudo efficiencies, i.e. calculated without series resistance losses, of 18.6% and 21.1% respectively (3 cm × 3 cm device area). These results reveal the potential of the ALD technique to deposit transition metal oxide (TMO) films as selective contacts on high efficiency devices, paving the way of using low thermal-budget, low cost and highly scalable processes for a highly demanding IBC solar cell architecture in the photovoltaic industry., Peer Reviewed

This is the peer reviewed version of the following article: Lopez-Garcia, A. [et al.]. Ultrathin wide-bandgap a-Si:H-based solar cells for transparent photovoltaic applications. "Solar RRL", 1 Gener 2022, vol. 6, núm. 1, p. 2100909:1-2100909:8. , which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1002/solr.202100909. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving., Herein, the fabrication of UV-blue selective transparent solar cells based on ultrathin (<30¿nm) intrinsic hydrogenated amorphous silicon films (a-Si:H) as absorber and using a fully inorganic architecture is reported, using metal-oxide thin films as carrier selective contacts and as transparent electrical contacts. These transparent ultrathin devices present a photovoltaic effect and high average visible transmittance (AVT), showing their potential as candidates for implementation as a transparent energy harvester. Potential applications range from Building-Integrated PV to agrophotovoltaics, and can also be of interest as a ubiquitous and inexpensive power source integrated in functional devices such as low-power devices, Internet of Things devices, and other sensors. Glass/FTO/ZnO/a-Si:H/MoO3/ITO device prototypes are produced. These devices present an AVT ranging from 50% to 69%, present a photovoltaic effect with a power conversion efficiency up to 0.5% calculated for an AM1.5G spectrum and have light utilization efficiency (LUE) values of 0.25%, confirming the potential of the proposed device architectures for the development of highly transparent devices with improved LUE., This work has received funding from the European Union H2020Framework Programme under Grant Agreement no. 826002(Tech4Win). This work is also part of the RþDþi MaterOne projects(Refs. PID 2020-116719RB-C42 and PID 2020-116719RB-C41) and ofthe RþDþi SCALED project (Ref. PID 2019-109215RB-C4) funded byMCIN/AEI/10.13039/5011000110033. Authors from IREC andUniversitat de Barcelona belong to the SEMS (Solar Energy Materialsand Systems) Consolidated Research Group of the“Generalitat deCatalunya”(Ref. 2017 SGR 862)., Peer Reviewed

According to intermediate band (IB) theory, it is possible to increase the efficiency of a solar cell by boosting its ability to absorb low-energy photons. In this study, we used a hyperdoped semiconductor approach for this theory to create a proof of concept of different silicon-based IB solar cells. Preliminary results show an increase in the external quantum efficiency (EQE) in the silicon sub-bandgap region. This result points to sub-bandgap absorption in silicon having not only a direct application in solar cells but also in other areas such as infrared photodetectors. To establish the transport mechanisms in the hyperdoped semiconductors within a solar cell, we measured the J–V characteristic at different temperatures. We carried out the measurements in both dark and illuminated conditions. To explain the behavior of the measurements, we proposed a new model with three elements for the IB solar cell. This model is similar to the classic two-diodes solar cell model but it is necessary to include a new limiting current element in series with one of the diodes. The proposed model is also compatible with an impurity band formation within silicon bandgap. At high temperatures, the distance between the IB and the n-type amorphous silicon conduction band is close enough and both bands are contacted. As the temperature decreases, the distance between the bands increases and therefore this process becomes more limiting., The authors would like to thank the Physical Sciences Research Assistance Centre
(CAI de Técnicas Físicas) of the Complutense University of Madrid. This study was
partially funded by Project MADRID-PV2 (P2018/EMT-4308), with aid from the
Regional Government of Madrid and the ERDF, by the Spanish Ministry of Science
and Innovation/National Research Agency (MCIN/AEI) under grants TEC2017-
84378-R, PID2019-109215RB-C41, PID2020-116508RB-I00 and PID2020-
117498RB-I00. Daniel Caudevilla would like to express his thanks for grant
PRE2018-083798, provided by the MICINN and the European Social Fund. Francisco
Pérez Zenteno would also like to express his thanks for grant 984933, provided by
CONACyT (Mexico)., Peer Reviewed

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., This work studies the use of thin layers of polyethylenimine (PEI) as an interface film to produce electron selective contacts for photovoltaic applications in crystalline silicon. Generally, in conjugated polyelectrolytes such as PEI with a high Lewis basicity, charge is accumulated along the chain of the polymer and counter anions from the solvent create an intense dipole array. In this work, part of the amine groups in PEI are protonated by the solvent that behaves as a weak Bronsted acid during the process. The PEI band modification is able to eliminate Fermi level pinning at metal/semiconductor junctions as it shifts the work function of the metallic electrode by more than 1 eV. As a consequence, induced charge transport between the metal and the semiconductor forms an electron accumulation region and promotes enhanced selectivity., This research has been supported by Spanish government
through Grants PID2019-109215RB-C41 (SCALED),
PID2019-109215RB-C43, PID2020-116719RB-C41 (MATER
ONE) and PID2020-115719RB-C21 (GETPV) and funded by
MCIN/AEI/ 10.13039/501100011033. Besides this the work is
also supported by the international Grants SENESCYT-2018
funded by Ecuadorian government., Peer Reviewed

In this work, a new design of transparent conductive electrode based on a graphene monolayer is evaluated. This hybrid electrode is incorporated into non-standard, high-efficiency crystalline silicon solar cells, where the conventional emitter is replaced by a MoOx selective contact. The device characterization reveals a clear electrical improvement when the graphene monolayer is placed as part of the electrode. The current–voltage characteristic of the solar cell with graphene shows an improved FF and Voc provided by the front electrode modification. Improved conductance values up to 5.5 mS are achieved for the graphene-based electrode, in comparison with 3 mS for bare ITO. In addition, the device efficiency improves by around 1.6% when graphene is incorporated on top. These results so far open the possibility of noticeably improving the contact technology of non-conventional photovoltaic technologies and further enhancing their performance., This research was funded by MCIN/AEI/10.13039/501100011033, grant numbers PID2019-109215RB-C41 and PID2019-109215RB-C42.